1. Field of the Invention
The invention relates to a grinding wheel that is used in a state where the grinding wheel is installed on a wheel spindle of a grinding machine.
2. Description of the Related Art
As a grinding wheel for a common grinding machine, a grinding wheel is available, in which a grindstone layer containing CBN or diamond is formed on an outer circumferential surface of a discoid grindstone core made of steel, in which an installation hole for use in installing the grinding wheel on a wheel spindle is formed in the center portion, and in which fixation hole portions for use in fixing the grinding wheel to the wheel spindle or the like are formed around the installation hole. As a grinding wheel for a grinding machine that rotates at a high speed, one that is described in Japanese Patent Application Publication No. 2002-200565 (JP-A-2002-200565), for example, is available, in which the grindstone core is made of aluminum alloy to reduce the weight of the discoid grindstone core. In the grinding wheel, a grindstone layer 35 is formed on the outer circumferential surface of a discoid aluminum alloy core 32 with an adhesive layer 34 interposed therebetween, an installation hole 45 for use in installing the core 32 to a wheel main spindle 21 is formed at a center portion of the core 32, and a plurality of fixation holes 55, 53, and 54 are formed around the installation hole 45 to fix a grinding wheel 31 to the wheel main spindle 21. The grinding wheel 31 is installed on a flange portion of the grinding main spindle 21 via a flange 51 etc. with the use of a plurality of installation bolts 52 through the fixation holes 55, 53, and 54. In addition, nickel-phosphorus (Ni—P) platings 70 and 71 for corrosion proof against a coolant are applied on the predetermined portions of the both end surfaces of the core 32, which portions can be splashed with coolant during grinding.
However, regarding the above-described related art, a situation sometimes occurs where, as machining of workpieces with the use of the grinding wheel is continued, the rotation balance of the grinding wheel is gradually lost, vibration occurs in the grinding wheel, and the chatter mark is imprinted on the ground surface of the workpiece, which results in the degradation of the plane accuracy. Conventionally, in order to ensure high plane accuracy of the machined surface, a measure has to be taken, in which the grinding machine is stopped during manufacturing and balancing of the grindstone is redone, or in which an expensive automatic balancer is introduced into the facility to correct the lost rotation balance.
After a diligent study of such a problem, the inventor has found that chippings, coolant mist, etc. suspended in the air attach to the grindstone core during grinding and the attached chippings are accumulated on the both end surfaces of the core, which can result in losing the rotation balance of the grinding wheel.